jakarta.persistence.ManyToMany Maven / Gradle / Ivy
/*
* Copyright (c) 2008, 2023 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0,
* or the Eclipse Distribution License v. 1.0 which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
// Contributors:
// Linda DeMichiel - 2.1
// Linda DeMichiel - 2.0
package jakarta.persistence;
import java.lang.annotation.Target;
import java.lang.annotation.Retention;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
/**
* Specifies a many-valued association with many-to-many multiplicity,
* mapping to an intermediate table called the join table.
*
* Every many-to-many association has two sides, the owning side
* and the non-owning, or inverse, side. The join table is specified
* on the owning side. If the association is bidirectional, either
* side may be designated as the owning side, and the non-owning side
* must use the {@link #mappedBy} element of the {@code ManyToMany}
* annotation to specify the relationship field or property of the
* owning side.
*
*
The join table for the relationship, if not defaulted, is
* specified on the owning side. The {@link JoinTable} annotation
* specifies a mapping to a database table.
*
*
The {@code ManyToMany} annotation may be used within an
* embeddable class contained within an entity class to specify a
* relationship to a collection of entities. If the relationship is
* bidirectional and the entity containing the embeddable class is
* the owner of the relationship, the non-owning side must use the
* {@link #mappedBy} element of the {@code ManyToMany} annotation to
* specify the relationship field or property of the embeddable class.
* The dot ({@code .}) notation syntax must be used in the
* {@code mappedBy} element to indicate the relationship attribute
* within the embedded attribute. The value of each identifier used
* with the dot notation is the name of the respective embedded field
* or property.
*
*
Example 1:
* {@snippet :
* // In Customer class:
*
* @ManyToMany
* @JoinTable(name = "CUST_PHONES")
* public Set getPhones() { return phones; }
*
* // In PhoneNumber class:
*
* @ManyToMany(mappedBy = "phones")
* public Set getCustomers() { return customers; }
* }
*
* Example 2:
* {@snippet :
* // In Customer class:
*
* @ManyToMany(targetEntity = com.acme.PhoneNumber.class)
* public Set getPhones() { return phones; }
*
* // In PhoneNumber class:
*
* @ManyToMany(targetEntity = com.acme.Customer.class, mappedBy = "phones")
* public Set getCustomers() { return customers; }
* }
*
*
Example 3:
* {@snippet :
* // In Customer class:
*
* @ManyToMany
* @JoinTable(name = "CUST_PHONE",
* joinColumns = @JoinColumn(name = "CUST_ID", referencedColumnName = "ID"),
* inverseJoinColumns = @JoinColumn(name = "PHONE_ID", referencedColumnName = "ID"))
* public Set getPhones() { return phones; }
*
* // In PhoneNumberClass:
*
* @ManyToMany(mappedBy = "phones")
* public Set getCustomers() { return customers; }
* }
*
* @see JoinTable
*
* @since 1.0
*/
@Target({METHOD, FIELD})
@Retention(RUNTIME)
public @interface ManyToMany {
/**
* (Optional) The entity class that is the target of the
* association. Optional only if the collection-valued
* relationship property is defined using Java generics.
* Must be specified otherwise.
*
* Defaults to the parameterized type of
* the collection when defined using generics.
*/
Class targetEntity() default void.class;
/**
* (Optional) The operations that must be cascaded to the
* target of the association.
*
*
When the target collection is a {@link java.util.Map},
* the {@code cascade} element applies to the map value.
*
*
Defaults to no operations being cascaded.
*/
CascadeType[] cascade() default {};
/**
* (Optional) Whether the association should be lazily
* loaded or must be eagerly fetched.
*
* - The {@link FetchType#EAGER EAGER} strategy is a
* requirement on the persistence provider runtime
* that the associated entity must be eagerly fetched.
*
- The {@link FetchType#LAZY LAZY} strategy is a hint
* to the persistence provider runtime.
*
*
* If not specified, defaults to {@code LAZY}.
*/
FetchType fetch() default FetchType.LAZY;
/**
* The field that owns the relationship. Required unless
* the relationship is unidirectional.
*/
String mappedBy() default "";
}